1. Field of the Invention
This invention is directed to top drive systems; parts thereof; and methods of their use.
2. Description of Related Art
The prior art discloses a variety of top drive systems; for example, and not by way of limitation, the following U.S. patent application and U.S. patents present exemplary top drive systems and components thereof: U.S. Pat. Nos. 4,458,768; 4,589,503; 4,753,300; 4,800,968; 4,807,890; 4,813,493; 4,872,577; 4,878,546; 4,984,641; 5,433,279; 6,007,105; 6,276,450; 6,536,520; 6,679,333; 6,705,405; 6,913,096; 6,923,254; 7,186,686; and 7,270,189 all incorporated fully herein for all purposes.
Certain typical prior top drive drilling systems have a derrick supporting a top drive which rotates tubulars, e.g., drill pipe. The top drive is supported from a traveling block beneath a crown block. A drawworks on a rig floor raises and lowers the top drive. The top drive moves on a guide track.
Certain prior systems include a top drive with a gear system with a lower or second stage planetary carrier which rotates with respect to multiple (e.g. two) vertically spaced-apart bearings which are secured in place and which do not float radially (or axially).